Internal combustion engine

ABSTRACT

An internal combustion engine includes a combustion chamber defined by a cylinder, a piston defining a piston top, a cylinder head with an intake port and an exhaust port, and a corresponding intake valve and an exhaust valve. The internal combustion engine further includes an intake manifold for supplying air to the combustion chamber and an exhaust manifold for drawing exhaust gas from the combustion chamber. The flow dynamics of the internal combustion engine are improved by including textured surfaces on one or more of the piston top, the cylinder head, the intake valve, the intake port, the exhaust valve, the intake manifold, the exhaust manifold, or the fuel supplier. The textured surface may include indentations, protrusions, or combinations.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is continuation of U.S. patent application Ser. No.13/142,960, filed Jun. 30, 2011, which is a National Phase PatentApplication and claims the priority to and the benefit of InternationalApplication Number PCT/US2009/069869, filed on Dec. 30, 2009, whichclaims priority to and the benefit of U.S. Provisional PatentApplication Ser. Nos. 61/141,987, filed Dec. 31, 2008 and 61/150,600,61/150,605, and 61/150,607, filed Feb. 6, 2009.

BACKGROUND OF THE INVENTION

This invention is directed to methods and apparatus for improving theflow dynamics and thermal characteristics inside an internal combustionengine.

SUMMARY OF THE INVENTION

In particular, this invention provides modifications to an internalcombustion engine which can provide benefits that include one or more ofimproving the flow dynamics of the intake system, combustion chamber andexhaust system, increasing air flow, providing better fuel atomizationand homogenization, achieving higher engine efficiency. Additionally,this invention can provide increased thermal control of the air passingthrough the intake, combustion chamber and exhaust system, which canreduce extreme temperature swings and provide increased power outputwith less fuel consumption.

An internal combustion engine according to an embodiment of theinvention includes a combustion chamber. For purposes of thisspecification, the combustion chamber may generally be defined by apiston top, a cylinder head defining an intake port and an exhaust port,an intake valve corresponding to the intake port, and an exhaust valvecorresponding to the exhaust port. While the embodiments of theinvention illustrated here generally refer to a single cylinder of aninternal combustion engine, it should be appreciated that the conceptsapply to multiple cylinder internal combustion engines. Furthermore,while each cylinder is generally described as having a single intakeport and a single exhaust port, the technology may be applied to engineshaving multiple intake ports or multiple exhaust ports per cylinder.Moreover, while the embodiments generally illustrate intake and exhaustvalves associated with each intake and exhaust port, the technology mayalso be applied to internal combustion engines such as two-cycle enginesthat operate without valves.

The internal combustion engine further includes an intake manifold forsupplying air to the combustion chamber and an exhaust manifold fordrawing exhaust gas from the combustion chamber. A fuel suppliercomprising one or more fuel injectors or one or more carburetorssupplies fuel to the combustion chamber of the internal combustionengine. The flow dynamics of the internal combustion engine are improvedby including textured surfaces on at least one of the piston top, thecylinder head, the intake valve, the intake port, the exhaust valve, theintake manifold, the exhaust manifold, or the fuel supplier. Accordingto certain embodiments, the shapes forming the textured surface may beindentations, protrusions, or combinations. Particular textured surfacesmay be dimples, prismatic shapes, pyramidal shapes, polyhedral shapes,conical shapes, portions of such shapes or combinations of such shapes.

In another embodiment of the invention, the internal combustion enginefurther includes a plurality of grooves generally located about theperimeter of a squish band defined by the cylinder head. In still otherembodiments, the textured inner surface further comprises a plurality ofhelical grooves located at an interface between the intake manifold andthe intake port, and an interface between the exhaust manifold and theexhaust port. In still other embodiments, the internal combustion engineincludes an air pressure booster such as a turbocharger or asupercharger where one or both of the compressor wheel and the turbinewheel are modified to include vanes with rounded edge surfaces toimprove the flow characteristics. Such air pressure boosters can alsoinclude tapered wall surfaces on one or more of an air inlet, acompressor outlet, a exhaust gas inlet, and an exhaust gas outlet tofurther improve the flow characteristics through the air pressurebooster.

In still other embodiments, one or more of the surfaces of the internalcombustion engine are coated with thermal barrier coatings to improvethe heat transfer characteristics of the internal combustion engine,contributing to improved performance.

The features of the invention change the surface physics of the intakesystem, combustion chamber and exhaust system to decrease the disruptionof air flow and increase the speed of the air-fuel mixture. When thesurfaces of the intake tracks are modified according to the invention,the increase of the speed of air or exhaust can provide benefits thatinclude increasing the horsepower and torque of the engine at a lowerthrottle input with lower fuel consumption. These modifications can alsoreduce the tendency for fuel to liquefy inside the intake track andcombustion chamber. By mitigating the re-liquefaction of atomized fuel,burn efficiency is increased and hydrocarbon emissions are decreased.

The improved flow and inclusion of thermal barrier coatings togetherhelp to control the temperatures of both the intake air and exhauststreams to further improve the combustion process. Features of theinvention contribute to a resultant combustible air-fuel mixture that isclose to 14.7:1 which is considered optimal for many internal combustionengines.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, together with the specification, illustratevarious aspects and embodiments of the invention.

FIG. 1 is a schematic cross sectional diagram illustrating a combustionchamber of an internal combustion engine;

FIG. 2 is a vector flow map for a conventional combustion chamber;

FIG. 3 is a cylinder head of an internal combustion engine according toan embodiment of the invention;

FIG. 4 is an exhaust valve of an internal combustion engine according toan embodiment of the invention;

FIG. 5 is an intake port of an internal combustion engine according toan embodiment of the invention;

FIG. 6. is a cylinder top of an internal combustion engine according toan embodiment of the invention;

FIG. 7 is a sectional view of a port insert for an internal combustionengine according to an embodiment of the invention;

FIG. 8 is a sectional view of a piston of an internal combustion engineaccording to an embodiment of the invention;

FIG. 9 is a partially exploded schematic illustration of a turbochargerfor an internal combustion engine according to an embodiment of theinvention;

FIG. 10 is a sectional view of a turbocharger air inlet for an internalcombustion engine according to an embodiment of the invention;

FIG. 11 is a sectional view of a turbocharger compressor outlet for aninternal combustion engine according to an embodiment of the invention;

FIG. 12 is a sectional view of a turbocharger exhaust gas inlet for aninternal combustion engine according to an embodiment of the invention;

FIG. 13 is a turbocharger turbine for an internal combustion engineaccording to an embodiment of the invention; and

FIGS. 14 through 16 are charts illustrating improved engine performanceusing embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

This technology helps to mitigate the formation of turbulent vortices orlow pressure areas that disrupt the intake track and the flow of fueland air in a combustion chamber of a typical internal combustion engine.FIG. 1 is a schematic sectional view of an internal combustion engine 2illustrating a combustion chamber 4 associated with a cylinder 6 of amultiple cylinder internal combustion engine. It should be noted thatthe internal combustion engine illustrated is a four-cycle sparkignition engine, but features of the invention may be applied to anyinternal combustion engine including two- and four-cycle spark ignitionand compression ignition engines.

A piston 8 is associated with each cylinder and reciprocates within thecylinder between intake, compression, combustion, and exhaust cycles fora four-cycle internal combustion engine. A cylinder head 12 seals thetop of the cylinder, and an inner wall 14 of the cylinder head togetherwith the piston top 16 generally define the combustion chamber of theinternal combustion engine. An intake valve 22 allows flow of air andfuel through an intake port 24 of the cylinder head and into thecombustion chamber. An exhaust valve 26 allows the exhaust to be drawnfrom the combustion chamber through an exhaust port 28. Each intakevalve and exhaust valve slides includes a shaft 32 extending through avalve guide 34 mounted within the cylinder head, and each valvereciprocates between open and closed positions. The valves are driven bya cam shaft (not shown) that controls the timing of the opening andclosing of each valve. A spark plug 35 is mounted in the cylinder headextending into the combustion chamber to provide an ignition source forthe combustion cycle. Upon combustion, the piston is pushed downwardwithin the cylinder driving a crank shaft (not shown) by a connectingrod 36 attached to the piston by a wrist pin 38.

Turning to FIG. 2, a cylinder head 12 is illustrated with arrows showingfluid flow within a conventional combustion chamber. Vaporization areas42 form around the perimeter of the compression chamber at the squishband 44, while misdirected air and fuel flowing into the combustionchamber from the intake port 24 causes the formation of vortices 46about the exhaust port 28. This misdirected air disrupts the mixture ofthe air and fuel causing droplets to form. The resulting liquefied fuelwashes into the combustion chamber, slowing the combustion during thecombustion cycle, and reducing the air-fuel mixture available to createpower during the compression cycle. This also results in incompletecombustion, increasing the emission of undesirable pollutants.

Current industry practice uses exhaust gas treatment components such ascatalytic converters, air injection, exhaust gas recirculation (EGR) andoxygen sensors to reduce emissions from unburned fuel. However,according to the present invention, engine performance can be improvedby changing the internal surface physics of the combustion chamber andrelated components. In embodiments of the invention, sharp internaledges are blended or reshaped to reduce the formation of low pressureareas in the intake and exhaust streams. Various textures or machinedpatterns may be added to the inside surfaces of the combustion chamberand related components. Without being bound by theory, the inventorsbelieve that when the air-fuel mixture passes over the modified surface,a boundary/acceleration layer is formed from the air-fuel charge passingover the modified surface. Within this layer, an adverse pressuregradient develops causing the air-fuel flow to separate from thesurface. This layer causes a laminar flow over this surface of thecombustion chamber to reduce the separation of the air-fuel mixture.which can occur with conventional technology where the fuel tends to beliquefied near the intake wall. The intake surface, without thismodification, normally results in higher air-fuel drag due to theseparation of the fuel from the air and droplets of fuel adhering to theintake surface.

By creating such a boundary/acceleration layer, the airflow speedincreases, promoting acceleration of the air-fuel mixture toward thecombustion chamber. The net result is improved fuel atomization andhomogenization with an increase in air-fuel velocity that promotes acylinder fill rate closer to a positive ratio. The increase in forwardmomentum also helps to maximize the volumetric air-fuel charge enteringthe combustion chamber during the intake stroke. This happensdynamically during the intake cycle of the air-fuel charge.

Turning to FIG. 3, a modified cylinder head 52 is illustrated withintake port 54, exhaust port 56, spark plug hole 58, and squish band 62.According to this embodiment, a plurality of dimples 64 are providedacross the inner surface of the cylinder head, and across the innersurface of the intake port in order to provide improved air-fuel flowinto and within the combustion chamber. In order to maintain propersealing of the inlet and exhaust valves, valve seating surfaces 66 donot include dimples. Flow grooves 68 are provided around the squish bandof the cylinder head, and optionally include additional dimples 72within the troughs formed by the flow grooves. The inclusion of flowgrooves at the squish band reduces the formation of vortices during theintake and compression cycles, and can be designed to force the air-fuelcharge to rotate in an appropriate direction to further mitigate theformation of vortices.

Referring to FIG. 4, in order to further improve flow within thecombustion chamber, exhaust valve 74 includes a valve face 76 with aplurality of dimples 78. Referring to FIG. 5, in order to improve flowof the air-fuel mixture into the combustion chamber, intake valve 82includes still more dimples 84 across its back surface 86. The innersurface of the intake port also includes a plurality of dimples 88. Inorder to maintain proper valve seating, the dimples do not extend to theportion of the back surface of the valve that abuts the valve seat, nordo the dimples extend to the valve shaft such that they might interferewith the sliding of the valve shaft within the valve guide 92. Turningto FIG. 6, the piston 94 includes a piston top 96 that also includesdimples 98 for improving air-fuel flow within the combustion chamber.

According to other embodiments of the invention, the intake port can bemodified to include helical grooves to improve and accelerate air flowto the combustion chamber. Referring to FIG. 7, an intake port insert102 is shown according to an embodiment of the invention. According tothis embodiment, the intake port insert is a ring-shaped insert that isdesigned to be placed between the intake manifold and the entrance tothe intake port at the cylinder head (see FIG. 1). The intake portinsert includes an inner wall defining a plurality of helical grooves104 that encourage vortex flow. The grooves may be formed such as bycasting or machining the inner wall. Adjacent grooves together formvanes 106 which accelerate the intake air flow velocity. The geometry ofthe grooves and vanes may be optimized based upon the specific intakeassembly to which the intake port insert is used. When placed directlyinto or between the intake port and intake manifold, the intake portinsert accelerates the air-fuel charge directed into the internalcombustion engine creating a vortex that causes a “boost effect,”drawing more air into the combustion chamber. This can lead better fuelatomization and homogenization which, in turn can lower fuel consumptionand increase performance. Furthermore, higher power output can beachieved at lower engine speed with smoother operation.

The angle or pitch of the grooves used in the intake port insert canproduce various ranges of improvement in the power output of an internalcombustion engine at different operating conditions. As an example,grooves with a finer pitch produce high initial power output at lowerinternal combustion engine speed. When the groove pitch is coarse, theimproved power output is realized at higher internal combustion enginespeed. Accordingly, the intake port insert can be customized to improvethe flow performance of a specific internal combustion engine's intakesystem by adjusting the pitch of the grooves. In general, the pitch ofthe grooves ranges between 15 degrees and 50 degrees. The depth, width,and shape of the grooves are also designed to optimize the accelerationof the intake air to an internal combustion engine.

According to certain embodiments of the invention, u-shaped, v-shaped,or similar shaped grooves are cut on an angle on the interior wall ofthe intake port insert. Groove spacing can be between about 2.5 mm andabout 12 mm depending on the application. The grooves can range betweenabout 2.5 and about 7.5 mm in depth depending on the application.Furthermore, dimpled surfaces can be added to further improve the flowcharacteristics. The use of dimpled surfaces is especially useful for aninternal combustion engine using throttle body fuel injection, acarburetor, or other system where the fuel and air are combined upstreamof the intake port.

According to the embodiment of the intake port insert illustrated atFIG. 7, an outer flange 108 of the intake port insert acts as a spacerbetween the intake port inlet and the intake manifold. However, in otherembodiments, the flange can be eliminated, and the intake port insertcan be fitted into a corresponding groove provided at either or both theinlet to the intake port, or the outlet from the intake manifold. Instill other embodiments, rather than providing the helical grooves on aseparate intake port insert, the grooves can be provided directly toeither or both of the inlet to the intake port, or the outlet from theintake manifold. For the embodiment where the helical grooves are to beprovided directly on the intake manifold, they can be machined afterfabrication, or can be incorporated directly into the mold used formaking an intake manifold.

Where the helical grooves are provided as a separate intake port insert,materials for fabrication include hard or elastomeric plastics, cast ormachined metals, or composite materials of various types. The materialselection is based upon its heat transfer characteristics and theoptimum location of the intake port insert in the internal combustionengine. According to one embodiment, an intake port insert is fabricatedfrom heat treated aluminum.

According to yet another embodiment, the exhaust port can be modifiedsimilarly to include helical grooves to improve and accelerate exhaustflow from the combustion chamber. According to one embodiment, anexhaust port insert substantially identical to the intake port insert ofFIG. 7 can be placed between the exhaust manifold and the exhaust portoutlet from the cylinder head. In another embodiment, the flange can beomitted and an exhaust port insert can be seated into a correspondinggroove provided at either or both the outlet from the exhaust port, orthe inlet to the exhaust manifold. In still other embodiments, ratherthan providing the helical grooves on a separate exhaust port insert,the grooves can be provided directly on either or both of the outletfrom the exhaust port, or the inlet to the exhaust manifold.

The inclusion of such helical grooves at the outlet from the exhaustport accelerates the hot exhaust gases by generating a vortex effect,resulting in an increase of power output. A “suction” effect can also berealized which increases the speed of the exhaust gases leaving thecombustion chamber at lower engine speed. Furthermore, such a featurebrings the internal combustion engine's intake air and exhaust air flowrates closer together to improve overall performance. This minimizes theretention of exhaust gases that can be drawn back into the combustionchamber during any valve overlap as may occur at the end of the exhauststroke and at the beginning of the intake stroke. During valve overlap,the air-fuel charge may be contaminated with excess exhaust gas,diluting the incoming air-fuel charge. This dilution can cause areduction in the effective air-fuel charge which in turn can cause areduction in power output for the internal combustion engine. Thegeometry and size of the helical grooves provided in the exhaust portoutlet generally correspond to those discussed above for the intake portinlet.

The intake and exhaust ports may also be flowed to determine the mostefficient direction of the ports and then checked for the percentage ofair flow increase at specifics lifts of the camshaft. The exhaust portmay be modified for flow enhancement to bring the flow differentialbetween the intake and exhaust ports closer together by maximize theexiting exhaust gases. The blending out of sharp edges and rougheningthe surface generally contributes to an increase in flow.

According to still other embodiments of the invention, such helicalgrooves can also be provided at the high-pressure air outlet housing ofa turbocharger or supercharger to accelerate the air-fuel charge to theinternal combustion engine and improve the efficiency of theturbocharger or supercharger. Such helical grooves can similarly beprovided at the exhaust gas exit of a turbocharger to accelerate andimprove the exhaust gas flow out of the turbocharger housing, improvingthe efficiency of the turbocharger.

While dimpled surfaces have generally been illustrated, there arenumerous ways to texture the surfaces. Furthermore, while indentationsare generally described, protrusions or raised surfaces using similargeometries will also provide good surface physics for the combustionchamber. Possible surface shapes include square, diamond or otherpolygonal-shaped indentations or protrusions that extend into or fromthe surface in prismatic, pyramidal, polyhedral or conical shapes, orportions or combinations of such shapes. Excellent results have beenshown for a surface textured with round indentations or dimples similarto the dimples on a golf ball. The shapes of the indentations or raisedsurfaces can generally have a width or diameter ranging from about 1.5mm to about 9.5 mm in one embodiment. In another embodiment the width ordiameter of the shapes generally ranges from about 2.5 mm to about 6.5mm. The depth or height of the indentations or raised surfaces can rangefrom about 0.5 mm to about 6.5 mm in one embodiment. In anotherembodiment the depth or height of the indentations or raised surfacesranges from about 2.5 mm to about 4 mm. In one embodiment, dimples areprovided that range in diameter from about 2.5 mm to about 6.5 mm with adepth of from about 2.5 mm to about 4 mm depending on the location inthe system.

According to other embodiments, a fuel injection throttle body or acarburetor assembly may be modified similarly with surface textures asdescribed above. In particular, the inclusion of textured surfaces onthe throttle body or carburetor assembly provide a larger surface areafor the air to be drawn over. Additionally, any sharp surfaces or edgesmay be blended to improve flow. The effect through the throttle body orcarburetor assembly creates an increase in available air for the engine.The textured surface may be provided at the air inlet of the filter,continuing up to and including the throat or entrance of the carburetoror throttle body. This increased air flow enhances the mixing effect atthe point where fuel is introduced.

According to still other embodiments of the invention, certain surfacesof the internal combustion engine may be coated with a thermal barriercoating. When applied around the combustion chamber, such thermalbarrier coatings can reduce the heat transfer away from the cylinderhead and re-direct the heat back in to the combustion chamber to reducea quenching effect and direct the subsequent combustion heat out theexhaust port. Examples of suitable thermal barrier coatings includealuminum-filled metallic ceramic coatings such as those made by TechLine Coatings, Inc. under the product names Tech Line CBC-2 and TechLine CBX.

Referring to FIG. 8, a sectional side view of a piston 94 isillustrated. The piston includes a piston top 96 with dimples 98 asdiscussed above. The modified piston top and the inner surfaces 112 ofthe piston skirt 114 and wrist pin side surfaces 116 of the piston caninclude similar thermal barrier coatings. Pistons coated with barriercoatings tend to run cooler, have less thermal growth and retain muchmore of their tensile strength. Barrier coatings also protect againsthigh temperature oxidation, reduce hot spots, and encourage proper flametravel. The barrier coating also spreads the heat evenly over the entirecoated surface, reducing detonation and pre-ignition, allowing the useof lower octane fuel. Furthermore, less heat is conducted through thewrist pins and connecting rods keeping the crank, bearings, oil andentire bottom end of the internal combustion engine cooler. The outersurface 118 of the piston skirts can optionally be coated with a solidfilm lubricant. One example of a suitable lubricant is made by Tech LineCoatings, Inc. under the name TLTD.

In addition such thermal barrier coatings may be applied to the intakeport inserts and exhaust port inserts described above. Both inside andoutside surfaces of such inserts may be coated. Use of such coatings onthe intake port inserts can reduce the heat transfer between the hotcylinder head and the intake manifold and can reduce thermal heattransfer into the air stream from the internal combustion engine.

Additionally, the interior surface of the exhaust port inserts mayoptionally be heat treated to improve the thermodynamics of the exhaustport inserts. To further improve the efficiency, the interior of theexhaust port inserts may be coated with thermal barrier treatments asdescribed above to retain the transfer of heat from the exhaust manifoldin the exhaust pipes. By maintaining the heat transfer from the cylinderhead exhaust port, the exhaust gases remain hot and minimize the effectof cooled exhaust gas. If the exhaust gases cool too quickly, the gasesbecome heavier causing them to slow down. The cooled gases can furthercreate a back pressure at the port, causing exhaust gas to re-enter thecombustion chamber on valve overlap.

According to still another embodiment of the invention, an improvedturbocharger is provided. Referring to FIG. 9, a turbocharger 132includes a compressor housing 134 which houses a compressor wheel (notshown) for boosting the pressure of ambient air. The air enters thehousing through an air inlet 136, is compressed by the compressor wheel,and exits thorough a compressor outlet 138 at an elevated pressure. Aturbine housing 142 adjacent the compressor housing uses exhaust gas atelevated pressure from the internal combustion engine to turn a turbine(not shown) that is directly linked to the compressor wheel by a commonshaft 144. The exhaust gas enters the turbine housing at an exhaust gasinlet 144, and exits the turbine housing through the turbine exhaust gasoutlet 146.

According to an embodiment of the present invention as shown in FIG. 10,the air inlet 136 includes a blended or tapered wall 152 in which theinner edge is blended towards the outer edge to improve the inlet airflow and increase the available volume on the compressor side of theturbocharger. As shown in FIG. 11, the compressor outlet 134 similarlyincludes a tapered wall 154 to improve the outlet air flow. Inparticular, modifying the compressor exit side of the compressor housingincreases the speed, volume, and pressure of the air delivered by theturbocharger to the intake manifold. This improves the internalcombustion engine's response at lower rpm. The tapered wall blendstowards the connection pipe between the compressor and the intakemanifold.

In yet another embodiment as shown in FIG. 12, the exhaust gas inlet 146of the turbine housing also includes a tapered wall 156 to similarlyimprove the flow characteristics. Though not shown, the exhaust gasoutlet can also include a tapered wall virtually identical to thetapered wall 152 of the air inlet 136 as shown in FIG. 10. Suchmodifications increase the speed of the exhaust gases through theturbine, improving the energy transferred to the compressed air.

In still other embodiments, one or both of the compressor wheel andturbine can be modified to improve the turbocharger's efficiency.Referring to FIG. 13, a partially modified compressor wheel 162 isillustrated. The compressor wheel includes a plurality of vanes 164which compress the air within the compressor housing. While conventionalvanes 166 generally include squared edges 168 with sharp corners,according to an embodiment of the invention, the modified vanes 172include rounded edges 174. By rounding and contouring the edges toeliminate sharp edges, the surface drag of the air against the vanes islowered, increasing the speed of the compressed air toward the intakesystem, and improving the turbocharger efficiency. Though not shown, aconventional turbine wheel is of a design similar to a compressor wheel,and includes vanes with generally square edges. According to yet anotherembodiment of the invention, the square edges on the vanes of theturbine wheel are rounded and contoured to eliminate sharp edges. Thisreduces surface drag of the exhaust gas against the turbine wheel vanes,increasing the speed of the exhaust gas through the turbine housing andimproving turbocharger efficiency.

Test results for an unmodified turbocharger show the intake temperaturestarted at 41° C., then climbed to 97° C. After the modifications, theintake air peaked at 44° C. This netted a 3° C. differential between theambient air and the intake air temperature. A lower intake airtemperature generally results in increased air density which leads toimproved fuel efficiency and increased power output.

According to still another embodiment of the invention, thermal barriercoatings can be applied to the inside surfaces of the compressor housing134 of a turbocharger 132 to block heat transfer, thereby maintaining alower temperature during the compression process. Similarly, thermalbarrier coatings can be applied to the inner and outer surfaces of theturbine housing 142 to maintain the heat inside the turbine housing. Tofurther minimize the heat transfer between the compressor housing andthe exhaust housing, a thermal barrier coating may be applied to theouter surfaces of a central bearing housing (not shown) between thecompressor housing and turbine housing. The use of such a coatingextends the life of the bearings and seal components and reduces theheat transfer between the turbine housing and compressor housing. Instill other embodiments of the invention, one or both of the compressorwheel and turbine wheel can be coated with thermal barrier coatings toreduce heat transfer between the turbine housing and compressor housing.

Suitable thermal barrier coatings include ceramic thermal barriercoatings. In certain embodiments, commercially available barriercoatings Tech Line's CBX or CBC-2 coatings may be used on the centralbearing housing and the exterior surface of the turbine housing of theturbocharger. The compressor wheel and turbine wheel may similarly becoated with CBX for thermal control. Tech Line's TLHB Hi Heat Coatingmay be used to coat the inside surfaces on the turbine housing of theturbocharger. While specific Tech Line products are mentioned, otherequivalent or similar products are available from other commercialmanufacturers, and may also be used.

The mechanical modifications and the application of thermal barriercoatings to various components of a turbocharger improve theturbocharger's performance through the entire RPM band. Improvements caninclude faster turbo response and improved low to mid-range throttleresponse. The application of thermal barrier coatings on thecompressor-side, turbine-side and bearing housings provide thermalcontrol which maximizes the overall efficiency. Tests have shown thatthe systematic application of this technology can result in a 5%-35%reduction in fuel consumption due to the reduction in throttle inputrequired for a given power output compared to a non-modifiedturbocharger. This results in more oxygen in the intake system at lessthrottle which improves power output, increases fuel mileage, andreduces tail pipe emissions. The lower air temperatures achieved by useof the invention may also allow the use of a smaller intercooler, andcould even eliminate altogether the need for an intercooler, reducingthe corresponding pressure loss associated with an intercooler.

While these embodiments are directed to turbocharger modifications, themodifications to the compressor side of the turbocharger could also beapplied to a supercharger or other types of air pressure boosters forinternal combustion engines. A supercharger includes an air compressorthat, rather than being driven by exhaust gas flowing through a turbine,is driven directly by the internal combustion engine such as by a beltlinked to the crank shaft. In particular, the compressor wheel of asupercharger can be modified to replace any sharp edges with rounded andcontoured edges as illustrated for the turbocharger at FIG. 13. The airinlet and compressor outlet of a supercharger can be modified to includetapered walls as illustrated for the turbocharger at FIGS. 9 and 10.Similarly, thermal barrier coatings can be applied to the compressorhousing and bearing housings of a supercharger to provide similarbenefits.

Advantages of the various embodiments of the present invention includethe ease with which existing internal combustion engine technology maybe modified. Existing components of the internal combustion engine,turbochargers, and superchargers can be machined using conventionalmetal working tools to include one or more embodiments of the presentinvention. The thermal compounds used in this invention are commerciallyavailable products.

One significant benefit of embodiments of this invention is an increasein engine efficiency. The increase in efficiency can be described as theincrease of output power with lower fuel consumption. Another way ofdescribing efficiency is a decrease in fuel consumed with equivalent orgreater power output. The application of this technology has shownincreases in efficiency by 15% to over 40%, depending on theapplication. This is accomplished by using less throttle input toachieve a power output that would normally require a wider throttleinput.

On a manufacturer's level, the application of this invention ortechnology is nearly transparent and very cost effective. The toolingchanges required to incorporate the dimples and surface textures are lowcompared to the increases in performance that may be attained. The netresult is lower fuel consumption and lower emission levels. Overallmanufacturing costs may decrease to the extent fewer or less complicatedemission devices may be required. The invention may also contribute to ahigher overall product reliability.

Example 1

A Cummins ISM heavy duty diesel engine with the Electronic ControlModule (ECM) set to produce 400 Hp and 1250 lb-ft was used as a testengine. This is a commonly used on-road truck engine. The engine wastested from a stabilized hot start using the test protocol in accordancewith the “transient cycle” Federal Test Procedure (FTP) established bythe United States Environmental Protection Agency. The FTP heavy-dutytransient cycle test is currently used for emission testing ofheavy-duty on-road engines in the United States, and was developed totake into account the variety of heavy-duty trucks and buses in Americancities, including traffic in and around the cities on roads andexpressways. The FTP transient test is based on the Urban DynamometerDriving Schedule (UDDS) chassis dynamometer driving cycle. The cycleincludes “motoring” segments and requires an electric dynamometercapable of both absorbing and generating power. The transient cycleconsists of four phases: the first is a New York Non Freeway (NYNF)phase typical of light urban traffic with frequent stops and starts. Thesecond is a Los Angeles Non Freeway (LANF) phase typical of crowdedurban traffic with few stops. The third is a Los Angeles Freeway (LAFY)phase simulating crowded expressway traffic in Los Angeles. The fourthphase repeats the first NYNF phase. There are few stabilized runningconditions, and the average load factor is about 20 to 25% of themaximum horsepower available at a given speed.

A baseline test was first performed on the stock un-modified engine.After the baseline test was completed the engine was modified usingseveral features of the present invention. In particular, the testengine included a cylinder head modified to include dimples, intake andexhaust port inserts, and turbocharger modifications as set forth above.

Emissions data from the testing is set forth in the following table:

Work Weighted Emissions (g/bhp-hr) Fuel Use (bhp-hr) HC CO NOx NO CO₂NMHC PM (lb/bhp-hr) Base 27.2 0.172 1.201 3.982 3.846 573.17 0.169 0.0820.3707 Test 27.3 0.184 1.225 3.920 3.845 552.28 0.181 0.071 0.3683 %Difference. 6.977 1.998 −1.557 −0.026 −3.645 7.101 −13.415 −0.647

The results show that the present invention can improve the performanceof the engine while reducing particulate matter (PM), oxides of nitrogen(NOx) and carbon dioxide (CO₂) within the constraints of the ECMprogram. The results also suggest that by tailoring the ECM mapping tothe subject technology, even greater benefits can be achieved. Inparticular, the increased hydrocarbon (HC), non-methane hydrocarbon(NMHC) and carbon monoxide (CO) results tend to show an over-rich fuelmixture. By mapping the ECM for a leaner burn, the efficiency of theengine can be improved. Furthermore, because the engine is limited bythe ECM to the specified horsepower and torque, the test does not showthe improved horsepower and torque potential that have been realized infield testing.

FIGS. 14 and 15 illustrate the turbo boost pressure and throttle outputvoltage for a portion of the LAFY phase of the test. These charts showthe relationship between throttle requirements to meet the demands ofthe test procedure and the response of the turbocharger. Overall, theturbo boost pressure of the test engine was at or higher than the turboboost pressure of the unmodified engine during the entire testprocedure. Similarly, the throttle output voltage for the test enginewas generally at or lower than that of the unmodified engine during theentire test procedure. However, the most pronounced improvement wasgenerally seen during the phases of the test that included periods ofheavy load. During such periods, the modified engine requiredsignificantly less throttle to meet the demand and the turbochargerresponded quicker and built more boost showing an increase in the totalefficiency of the engine.

Furthermore, the tests show that the technology of the present inventionheld engine temperatures lower on average, contributing to a reductionin NOx emissions. Typically an increase of engine efficiency and reducedfuel consumption will result in an increase in temperature and anincrease in NOx emissions.

Example 2

For Example 2, a turbo-charged Cummins 5.9 liter diesel engine wasmodified according to features of the present invention. In particular,the engine was modified to include dimples and flow grooves on thecylinder heads, dimples on the piston tops, the exhaust valve faces, theintake ports, and the back surfaces of the intake valves, inserts withhelical grooves at the high-pressure air outlet of the turbocharger,modified compressor and turbine wheels as explained above, tapered wallson the compressor inlet and outlet, and on the turbine inlet and outletof the turbocharger, and thermal barrier coatings as explained above.However, prior to these modifications, the unmodified engine was“mapped” by mounting the engine to a dynamometer and measuring the peaktorque and horsepower generated at the engine's primary output shaft atvarious engine speeds. The engine was then modified as explained above,again mounted to the dynamometer, and mapped a second time. The protocolfor such engine mapping is based on the EPA revised regulations 40 CFR§1065.510.

FIG. 16 illustrates the power output portion of the results of thisengine mapping where, for each of the unmodified engine and the engineof Example 2, the peak horsepower output of the engine is graphed atvarious engine speeds. The engine mapping shows that enginemodifications of embodiments of the present invention can result in a25% increase in torque at 1600 RPM and an 18% increase in horsepower at2500 rpm.

Specific embodiments of the invention have been illustrated, many ofwhich are directed to four-cycle spark ignition engines. However, thevarious features may be applied to other types of engines includingtwo-cycle spark ignition engines, and two- or four-cycle compressionignition engines.

What is claimed is:
 1. An internal combustion engine comprising: atleast one cylinder; at least one piston received in the at least onecylinder; at least one cylinder head coupled to the at least onecylinder defining at least one intake port and at least one exhaustport; a combustion chamber defined by the at least one cylinder head anda top of the at least one piston; at least one intake valvecorresponding to the at least one intake port; at least one exhaustvalve corresponding to the at least one exhaust port; an intake manifoldadapted to supply air to the combustion chamber; a fuel suppliercomprising one or more fuel injectors or one or more carburetors adaptedto supply fuel to the combustion chamber; and an exhaust manifoldadapted to direct a flow of exhaust gas from the combustion chamber,wherein at least one of the at least one cylinder head, the at least oneintake valve, or the at least one exhaust valve includes a surfacecomprising a plurality of surface features arranged in a matrix-likepattern.
 2. The internal combustion engine of claim 1, wherein thesurface features are selected from the group consisting of indentations,protrusions, and combinations thereof.
 3. The internal combustion engineof claim 1, wherein a plurality of the surface features aresubstantially the same size.
 4. The internal combustion engine of claim1, wherein the matrix-like pattern is a rectilinear grid.
 5. Theinternal combustion engine of claim 1, wherein the matrix-like patternis a contoured grid.
 6. The internal combustion engine of claim 1,wherein the surface features are selected from the group consisting ofdimples, prismatic shapes, pyramidal shapes, polyhedral shapes, conicalshapes, portions of such shapes, and combinations thereof.
 7. Theinternal combustion engine of claim 1, wherein a plurality of thesurface features have an average width of about 1.5 to about 9.5 mm, andan average depth or height of about 0.5 to about 6.5 mm.
 8. The internalcombustion engine of claim 1, further comprising a plurality of groovesgenerally located about a perimeter of a squish band defined by thecylinder head.
 9. The internal combustion engine of claim 8, furthercomprising a plurality of surface features in each of the plurality ofgrooves.
 10. The internal combustion engine of claim 1, furthercomprising a plurality of helical grooves located at at least one of theintake port, the exhaust port, an interface between the intake manifoldand the cylinder head, or an interface between the exhaust manifold andthe cylinder head.
 11. The internal combustion engine of claim 10,further comprising a plurality of surface features within the helicalgrooves.
 12. The internal combustion engine of claim 1, furthercomprising a thermal barrier coating on a surface of at least one of theat least one cylinder, the at least one cylinder head, the at least onepiston, the at least on intake valve, the at least one exhaust valve,the intake manifold, or the exhaust manifold.
 13. The internalcombustion engine of claim 1, further comprising an air pressure boosterselected from a turbocharger and a supercharger.
 14. An internalcombustion engine comprising: at least one cylinder; at least one pistonreceived in the at least one cylinder; at least one cylinder headcoupled to the at least one cylinder defining at least one intake portand at least one exhaust port; a combustion chamber defined by the atleast one cylinder head and a top of the at least one piston; at leastone intake valve corresponding to the at least one intake port; at leastone exhaust valve corresponding to the at least one exhaust port; anintake manifold adapted to supply air to the combustion chamber; a fuelsupplier comprising one or more fuel injectors or one or morecarburetors adapted to supply fuel to the combustion chamber; and anexhaust manifold adapted to direct a flow of exhaust gas from thecombustion chamber, wherein at least one of the intake port, the exhaustport, an interface between the intake manifold and the cylinder head, oran interface between the exhaust manifold and the cylinder headcomprises a plurality of helical grooves.
 15. The internal combustionengine of claim 14, wherein the helical grooves have a pitch fromapproximately 15 degrees to approximately 50 degrees.
 16. The internalcombustion engine of claim 14, wherein the helical grooves are u-shapedor v-shaped in cross-section.
 17. The internal combustion engine ofclaim 14, wherein spacing between adjacent ones of the plurality ofhelical grooves is from approximately 2.5 mm and approximately 12 mm.18. The internal combustion engine of claim 14, wherein a plurality ofthe helical grooves have an average depth from approximately 2.5 mm andapproximately 7.5 mm.
 19. The internal combustion engine of claim 14,wherein the helical grooves are integral to at least one of the intakemanifold, the exhaust manifold, or the cylinder head.
 20. The internalcombustion engine of claim 14, wherein the helical grooves are definedin a removable insert.